Quinoline Functionalized Schiff Base Silver (I) Complexes: Interactions with Biomolecules and In Vitro Cytotoxicity, Antioxidant and Antimicrobial Activities

Abstract

A series of fifteen silver (I) quinoline complexes Q1–Q15 have been synthesized and studied for their biological activities. Q1–Q15 were synthesized from the reactions of quinolinyl Schiff base derivatives L1–L5 (obtained by condensing 2-quinolinecarboxaldehyde with various aniline derivatives) with AgNO3, AgClO4 and AgCF3SO3. Q1–Q15 were characterized by various spectroscopic techniques and the structures of [Ag(L1)2]NO3Q1, [Ag(L1)2]ClO4Q6, [Ag(L2)2]ClO4Q7, [Ag(L2)2]CF3SO3Q12 and [Ag(L4)2]CF3SO3Q14 were unequivocally determined by single crystal X-ray diffraction analysis. In vitro antimicrobial tests against Gram-positive and Gram-negative bacteria revealed the influence of structure and anion on the complexes′ moderate to excellent antibacterial activity. In vitro antioxidant activities of the complexes showed their good radical scavenging activity in ferric reducing antioxidant power (FRAP). Complexes with the fluorine substituent or the thiophene or benzothiazole moieties are more potent with IC50 between 0.95 and 2.22 mg/mL than the standard used, ascorbic acid (2.68 mg/mL). The compounds showed a strong binding affinity with calf thymus-DNA via an intercalation mode and protein through a static quenching mechanism. Cytotoxicity activity was examined against three carcinoma cell lines (HELA, MDA-MB231, and SHSY5Y). [Ag(L2)2]ClO4Q7 with a benzothiazole moiety and [Ag(L4)2]ClO4Q9 with a methyl substituent had excellent cytotoxicity against HELA cells.

Ag(I) Complexes of Imine Derivatives of Unexpected 2-Thiophenemethylamine Homo-Coupling and Bis-(E)-N-(furan-2-ylmethyl)-1-(quinolin-2-yl)methanimine

“…A slightly modified procedure from our group was also used [22,23] in the synthesis of the Ag(I) complexes as shown in Scheme 2a,b.…”

Synthesis and potential antimicrobial activity of novel α-aminophosphonates derivatives bearing substituted quinoline or quinolone and thiazole moieties

“…Many scientific reports revealed that natural and synthetic quinolines are drawn considerable attention in medicinal chemistry [ 7 , 8 ]. The great attention paid by researchers to the study of quinoline derivatives is explained by their broad range of biological activities, such as anti-Alzheimer [ 9 ], antidiabetic [ 10 ], anti-inflammatory [ 11 ], antituberculosis [ 12 ], anticancer [ 13 ], antioxidant [ 14 ], and as inhibitors of SARS‐CoV‐2 (COVID-19) virus [ 15 – 17 ]. Therefore, compounds containing thiazole heterocycles are well known in medicinal chemistry [ 18 ], thiazole derivatives exhibit significant biological activities, such as antimicrobial and antimalarial [ 19 ], Alzheimer [ 20 ], antiproliferative agents [ 21 ], anticancer agents [ 22 ], and anti-inflammatory [ 23 ].…”

Different Schiff Bases—Structure, Importance and Classification

“…In recent years, there has been greater interest in the possibility of using metal ions such as Ag(I), Au(I) or Pt(II) in medicine [ 27 , 28 ]. Additionally, complexes of these metals with Schiff’s bases show interesting biological properties [ 29 , 30 , 31 , 32 , 33 ].…”